More than a century after King Leopold II of Belgium claimed Congo as his personal colony, an unprecedented investigation into Belgium's murky colonial past and long-ignored allegations of genocide is to be held.

To the fury, no doubt, of Belgium's dwindling band of "old colonials" the state-funded Royal Museum for Central Africa - formerly known as the Museum of the Belgian Congo - has commissioned some of the country's most eminent historians to give the public the one thing they have been deprived of for so long: the truth.

Shocking claims - often well documented - that 10 million Congolese were either murdered or worked to death by Leopold's private army, that women were systematically raped, that locals' hands were cut off and that the local populace endured kidnapping, looting and village burnings, have never been the subject of serious debate in Belgium, let alone an apology.

Many of these allegations are set out in a book called King Leopold's Ghost by the American author Adam Hochschild. When it was published in Belgium in 1999 it outraged the country's historians but failed to bring about a genuine period of reflection.

Controversially, Hochschild compared the death toll in the Belgian-administered Congo to the Holocaust and Stalin's purges.

"We will look at these claims, we will investigate them and by 2004 we will attempt to provide an answer to Hochschild's book," Guido Gryseels, the director of the museum, said.

"We cannot avoid answering these questions. It has become too much of an issue. Everyone raises it all the time and we don't know what to say."

The investigation will force the country to confront its colonial demons and tackle a subject which has been taboo ever since the Welsh-born explorer Henry Morton Stanley secured the rubber- and ivory-rich colony for Leopold in 1885.

The investigatory panel, likely to be headed by Professor Jean-Luc Vellut, will start work in the next two months and present its findings in 2004 (the centenary of Stanley's death) as part of an exhibition at the museum.

If Congo is Belgium's forgotten skeleton then the museum is its neglected cupboard. An imposing palace near Brussels built by Leopold with money he made in Congo to showcase a place he never visited, it is crammed with millions of objects brought back in dubious circumstances.

Tatty stuffed animals vie for attention with display cases crammed with butterflies, fish and African tribal art, but the museum, like much of Belgium itself, is frozen in a colonial time warp.

It commemorates the Force Publique officers, who are now accused of barbarism. And of the cruelty and suffering endured by the Congolese people there is no mention.

It is a desire to modernise the museum and drag it out of its one-sided politically incorrect past that has prompted the investigation.

"The museum hasn't changed for the last 44 years," Mr Gryseels conceded.

"It has a colonial spirit to it. As you walk in there is a statue [of a black boy looking up at a white missionary] with the legend 'Belgium brings civilisation to the Congo'.

"The message of the museum needs to change so that it doesn't only reflect the view of Belgium before 1960 [when Congo won its independence]. We need African views too so that the visitor can make up their own mind."

More than a century may have passed since Leopold acquired Congo, embracing territory the size of western Europe, but sensitivity about Belgian culpability remain acute.

"It is a reality which touches the deepest part of the Belgian soul," Mr Gryseels said. "We really haven't coped with it, and the revelations came as a real shock. We were brought up knowing that we brought civilisation and good to Africa. [Allegations of brutality] weren't taught in schools."

The investigation will be only the first step towards coming to terms with the past.

Disbelief about the seriousness of the allegations and a feeling that foreign historians are over influenced by works such as Joseph Conrad's Heart of Darkness, in which the terrible Kurtz has African heads on spikes in his front garden, runs deep - even among the historians invited to investigate the matter.

"To compare it with the Holocaust or Auschwitz is an insult to the truth," Prof Vellut said. "We need to put our history in perspective and be cautious."

Many of the specific allegations cannot, he conceded, be disputed but he argued that discovering the precise scale of the atrocities would be difficult.

"Statistics for that period are very unreliable. One hardly knew what the population was. You can see figures which make the Jewish slaughter pale in comparison. Who knows whether 10m or 15m Congolese were killed?"

King's plunder

· King Leopold II appointed himself King Sovereign of Congo Free State in 1885

· In 1908, a year before his death, he sold the colony to the Belgian state, which governed it until independence in 1960

· Belgian Congo was 76 times bigger than Belgium itself

· Rudyard Kipling called it the place "where there are no 10 commandments"

· The instrument of Belgian repression was the chicotte - a whip made from sun-dried hippo hide

· Leopold's fortune - which he ploughed back into monumental buildings in Brussels - was made on the proceeds of Congolese rubber and ivory

· Locals were forced to collect the sap required to produce rubber or, it is alleged, have their hands or feet, or those of their children, cut off

· Between 1880 and 1920 the population of Congo halved. The writer Adam Hochschild claims that 10 million people were the victims of murder, starvation, exhaustion induced by over-work, and disease

· The plight of the Congolese, and Belgian brutality were first brought to the world's attention at the beginning of the 20th century by American and British campaigners and writers